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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Marine biology 23 (1973), S. 47-57 
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Initiation of coral-skeleton formation was studied in the reef-coral Pocillopora damicornis Lamarck. Observations were made on sequential skeletal growth stages of newly settled planula larvae during the first 22 days following settling onto glass microscope slides. Techniques used include phase light microscopy, scanning and transmission electron microscopy, and powder X-ray and selected area electron micro-diffraction. Formation of the skeleton is initiated immediately on settling of the larva. The primary calcareous elements are of two types — flattened spherulitic platelets, and smaller rod-like granules. Rudimentary primary septa are clearly defined within 6 h after settling. Fusion of the primary calcareous elements results in the formation of the larval basal disc within 48 to 72 h. With transmission electron microscopy, this basal disc is found to differ from subsequent adult calcification in (1) considerably lesser degree of mineralization, (2) smaller crystal size, (3) more random orientation of the crystals, and (4) the presence of trace amounts of calcite in addition to aragonite. The basal disc with its septal rudiments constitutes a true larval skeleton, differing in morphology, micro-architecture, and crystal type from the fibrous growth characterizing the adult skeleton.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A sharp increase in alkaline phosphatase (AP) activity occurred 7 d after arm autotomy inAsterias forbesi. This activity remained elevated at 20 d post-autotomy, during which time active ossicle-calcification was occurring. By 60 d post-autotomy, AP activity had returned to the level of non-regenerating individuals. Conversely, carbonic anhydrase (CA) activity exhibited no initial change in response to arm autotomy. By Day 60 a 50% increase in CA activity was observed. AP is localized in the outer membranes and associated microvilli of the coelomic epithelium and is not associated directly with the tissues involved in calcification. CA activity was highest in the tissues containing the ossicles, but was also present in the non-calcifying tube feet. These data suggest that inA. forbesi AP is involved in cell division and differentiation associated with wound-healing and the initiation of the regeneration process, and that CA may facilitate the ongoing maturation process, of newly formed ossicles.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 16 (1974), S. 283-291 
    ISSN: 1432-0827
    Keywords: Snails ; Vaterite ; Calcium ; Storage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Large quantities of calcium carbonate crystals were present in the albumin gland of the reproductive system of the fresh-water snailPomacea paludosa. X-ray diffraction analyses indicated that they were vaterite. Scanning electron microscope observation of the albumin gland revealed that they occurred as spherules and were distributed throughout the gland. Vaterite spherules were present in the albumin gland ofPomacea urceus and the capsule gland ofPila virens. The mineral portion of the egg capsules was also vaterite. The egg capsule of these snails consisted of two morphologically distinct layers. Vaterite is less common in nature than the other two polymorphs of calcium carbonate, calcite and aragonite, and has not been recorded in the reproductive system of molluscs. It is interesting to note that in these snails calcium carbonate was present as vaterite both in the storage organ and fully differentiated egg capsule.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 1 (1967), S. 114-121 
    ISSN: 1432-0827
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Des études de microscopie électronique montrent que les coccolithes deCoccolithus huxleyi sont constitués par des pièces disposées de façon radiaire; chaque élément comporte un segment supérieur et inférieur ainsi qu'une paroi centrale. La diffraction électronique montre que chaque pièce consiste en un monocristal de calcite ayant la forme d'un cristal creux. L'axe est paralléle à l'axe longitudinal de l'élément. Les surfaces du sommet et de la base de l'élément inférieur et la surface basale de l'élément supérieur sont constituées vraisemblablement par les plans (010).
    Abstract: Zusammenfassung Elektronenmikroskopische Beobachtungen zeigen, daß der Kokkolith vonCoccolithus huxleyi aus radialstrahlig angeordneten Einheiten besteht mit je einem oberen und einem unteren Element, sowie einer Wand in der Mitte. Die Ergebnisse der Elektronenstrahlbeugung lassen jede Einheit als einen Kalkspat-Einkristall in Form eines Hohlkristalls erscheinen. Die c-Achse liegt parallel zur Verlängerung des Elements. Die obere und die Grundfläche des unteren Elements sowie die Grundfläche des oberen Elements sind wahrscheinlich (010) Ebenen.
    Notes: Abstract Electron microscope observations show that the coccolith ofCoccolithus huxleyi is composed of radially arranged units, each consisting of an upper and lower element and a central wall. From the results of electron diffraction analysis the whole unit is considered to be a single crystal of calcite having the form of a hollow crystal. The c-axis is oriented parallel to the direction of elongation of the element. The top and bottom sufaces of the lower element, and the bottom surface of the upper element are probably (010) planes.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Comparative Biochemistry and Physiology -- Part B: Biochemistry and 94 (1989), S. 651-654 
    ISSN: 0305-0491
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Comparative Biochemistry and Physiology -- Part B: Biochemistry and 76 (1983), S. 443-447 
    ISSN: 0305-0491
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Comparative Biochemistry And Physiology 29 (1969), S. 611-620 
    ISSN: 0010-406X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Progress In Crystal Growth And Characterization 4 (1981), S. 99-147 
    ISSN: 0146-3535
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0047-6374
    Keywords: Aged mice ; Senescent deterioration ; Streptococcus lactis ; Superoxide dismutase
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Comparative Biochemistry and Physiology -- Part A: Physiology 60 (1978), S. 207-211 
    ISSN: 0300-9629
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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